I get good use out of paring a Silky 130 Pocketboy XL-teeth with a Koster Bushcraft. :thumbup:
For a lightweight/inexpensive-backup, the Gerber/Fiskars Retractable more than pulls its weight (teamed with a Mora 510, of course!

).
Silky PB130 has solid lockup, with no noticeable bladeplay (may be loosened/tightened); teeth are very sharp and go through material much faster than the Fiskars, even though the blade is shorter. It also comes with a plastic case with included belt attachment option; blades are interchangeable, for new sharpness, or different XS-XL sized teeth. I think Dale (or someone), in another thread, said their Silky 130 felt like a real quality tool, and I would agree.
Pocketboy 170 might be a consideration, balancing if you'd like a little extra length and how you'll be carrying it, more or less. I would have gotten one of these, if the store I ordered from stocked them, but I don't feel the least bit under-sawed

Fiskars packs up in less space & weight (I believe, not sure, approx half-weight of Silky 130). I've never been disappointed with it, and have got plenty of good use out of it; although it has taken a backseat since receiving the Silkies, and I was always conscious not to push it. Teeth do not seem as sharp, doesn't start a cut as easily, and are not impulse-hardened tips. Lockup is far from solid, but being retractable, it won't collapse on your fingers. Slight trade-off in time/energy invested vs speed of cut.
In a woods kit, the Fiskars retractable saw and a Mora weigh less than a Leatherman Wave, and seem to get more use in that situation, for me personally. Fiskars is very inexpensive at $10 shipped, and I would suggest that to begin with/in addition, until you really lock in on what would work.
Fiskars Folding saw, as opposed to Retractable, I view much less favorably, and would not personally recommend; construction seems more solid, but greater difficulty in starting and completing cuts, with a coarse/ragged finish. Seemingly much less effective at a greater size/weight.
The Opinel saw Powernoodle posted has been catching my eye for a long time now, too! I will need to remember to capture one, one day. Not sure where to find that version, and not the larger one at SMKW. It definitely is the looker of the bunch, and the one most likely to gain character quickly from modification, use, or otherwise; lightweight, I'd guess. Unfortunately, the idea of your blade/saw getting wet and swelling into effectively locked in closed position is not favorable, and would likely use this one in a backup role, just because I like it :foot: